1. Voice Over Internet Protocol
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VOIP SYSTEMS
VOIP
Voice Over Internet Protocol
F. BARTIER – IPSS – 12/02/2008

2. Classical VOIP system

3. VOIP elements definitions
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VOIP elements definitions
IPBX
Intranet Private Branch eXchange
IP based version of a conventional Private branch exchange (PABX or PBX)
Like a classical server dedicated to the phone system
ATA or IP gateway:
Analog Telephony Adapter
Device used to connect one or more standard analog telephones to a digital world (most of the time IP based)

4. How to have analog lines on VOIP system?
Directly through the IPBX
With an analog interface board installed in the IPBX
Each analog output may need special configuration depending on the analog terminal type (phone, fax, modem)
Near the analog devices with ATA appliances
Each ATA analog output:
Is always integrated in the global phone system
Is seen as a analog terminal
May need special configuration depending on the analog terminal type (phone, fax, modem)

5. IPBX example (Hipath 1120) A, B: Regular analog telephone
C, D: 10BaseT category-5 cable to access IP network
E: Power for AC/DC power adaptor
Entry level solution already seen in small countries (Switzerland, Belgium, Norway,…)

6. 2/15/2019
IPBX Example (HiPath 1120)

7. ATA Example (Cisco ATA 186)
A: Regular analog telephones (two)
B: 10BaseT category-5 cable to access IP network
C: Power for AC/DC power adaptor
Most of the time, added in system with an IPBX to connect additional analog lines

8. ATA example (Cisco ATA 186)
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ATA example (Cisco ATA 186)

9. Differences between IPBX and ATA
IPBX is a server dedicated to manage phones. For example:
Manage the phone equipments (locked, absent, busy, free)
Convert phone number to IP address
Manage common phone directories …
Sometime, it integrates also analog outputs
ATA is a converter IP-Analog
IP on one side
Analog on the other

10. Main characteristics of an ATA
Provide analog lines on VOIP based systems
Classically parameters are modifiable via a Web server included in the appliance
Regarding network interface
IP settings
Quality Of Service for IP packets
Regarding Analog interface
Tone
Dialing methods
Regarding VOIP parameters
Phone number, name, …
Codec used (i.e. voice coding and compression)
Voice quality enhancement

11. ATA main troubles with modems connections
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ATA main troubles with modems connections
Some codecs are only dedicated to voice
G726, G729 are a compression algorithms (sometime with loss) acceptable for voice but not for digital data.
Silent elimination
When no voice is detected, ATA can suppress all the signal
Incompatible with data transmission.
Echo cancellation
To suppress echo effect
Delay during exchange
Delay in transmission could be added to compress or remove artefacts. Same behavior can occur for answer-back channel
Delay can occur also due to network availibility
Risk to Loose synchronization between exchanged message
Risk of time-out

12. ATA bad effects example
Modem transmission without echo cancellation
Modem transmission with echo cancellation

13. ATA configuration to work with modem
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ATA configuration to work with modem
Modem or fax could work correctly with ATA
By using standardized protocol to announce that they are a data transmission terminal:
T38 for Fax
V8 for Modem
ATA works then in transparent mode (no compression, no silent elimination, no echo cancellation)
By forcing the ATA to work by default in transparent mode
However delay on Network could always lead to synchronization lost

14. V8 protocol is not supported by the TD and Ingenico in IJ range modems
IJ modems and VOIP
V8 protocol is not supported by the TD and Ingenico in IJ range modems
Currently, only one valid solution:
Request to customer using VOIP and ATA to modify their ATA settings in order to work in transparent mode for Mailing system analog line
Case by case configuration when system installation
Long term solution: An evolution of the software (inside the modem) is required to support V8 or eventually T38 protocol

15. Delta modem and VOIP
V8 protocol is not supported by the TD modem but theorically is supported by the Ingenico modem
Currently, only one valid solution:
Request to customer using VOIP and ATA to modify their ATA settings in order to work in transparent mode for Mailing system analog line
Alternative short/Mid term solution: Use the Lan connection
Communication natively IP based, no Digital to analog then analog to IP is needed
Case by case usage for Customer using not working VOIP equipments
Mid term solution: Qualify the Ingenico Modem on VOIP environment with a selected ATA appliances.